Inhibitory effect of cysteine and methionine on free radicals induced by mercury in red blood cells of patients undergoing haemodialysis.

The inhibitory effects of cysteine and methionine on mercury-induced free radicals were studied in the red blood cells (RBC) of haemodialysed (HD) patients, using polyacrylonitrile membranes. RBC were taken from a control group of 10 healthy subjects and a group of 30 HD patients. The following were determined before and after HD: malonyldialdehyde (MDA), total glutathione (GST), reduced (GSH) and oxidized (GSSG) glutathione, and percentage haemolysis (before HD). RBC were incubated for 6 hr with mercury (Hg(2+); 10(-5)m), mercury and cysteine (0.001 m) and mercury and methionine (0.005 m). The percentage of mercury induced haemolysis differed between the control group and HD patients. The addition of cysteine and methionine to RBC has a markedly inhibitory effect on the mercury-induced haemolysis (a reduction from about 80 to 5% for cysteine and to 15% for methionine). MDA was increased in HD patients and increased further after HD. GST, GSH and GSSG were lower than normal in HD patients, both before and after HD. There was very little change in MDA concentration when the RBC were incubated with mercury for 6 hr.